Liquid crystal composition and liquid crystal display device

ABSTRACT

To provide a liquid crystal composition satisfying at least one characteristic such as a high maximum temperature of a nematic phase, a low minimum temperature thereof, a small viscosity, a suitable optical anisotropy, a large negative dielectric anisotropy and specific resistance, a high stability to ultraviolet light and heat, or a liquid crystal composition having a suitable balance regarding at least two characteristics; an AM device having a short response time, a large voltage holding ratio and contrast ratio, a long service life and so forth; wherein the liquid crystal composition contains a specific compound having a polymerizable group as a first component, and may contain a specific compound having a large negative dielectric anisotropy and a low minimum temperature as a second component, or a specific compound having a small viscosity or a large maximum temperature as a third component, and a liquid crystal display device contains the composition.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a 371 of international application of PCTapplication serial no. PCT/JP2011/060629, filed on May 9, 2011, whichclaims the priority benefit of Japan application no. 2010-110159, filedon May 12, 2010. The entirety of each of the above-mentioned patentapplications is hereby incorporated by reference herein and made a partof this specification.

TECHNICAL FIELD

The invention relates to a liquid crystal composition containing apolymerizable compound that is polymerized, for example, by light orheat. The invention also relates to a liquid crystal display device inwhich the liquid crystal composition is sealed between substrates, andthe polymerizable compound contained in the liquid crystal compositionis polymerized while adjusting a voltage to be applied to a liquidcrystal layer to immobilize alignment of liquid crystals.

As the technical field of the invention, the invention relates to aliquid crystal composition mainly suitable for use in an active matrix(AM) device and so forth, and an AM device and so forth including thecomposition. More specifically, the invention relates to a liquidcrystal composition having a negative dielectric anisotropy, and adevice and so forth that include the composition and have a mode such asan in-plane switching (IPS) mode, a vertical alignment (VA) mode or apolymer sustained alignment (PSA) mode. The VA mode includes amulti-domain vertical alignment (MVA) mode and a patterned verticalalignment (PVA) mode.

BACKGROUND ART

In a liquid crystal display device, a classification based on anoperating mode for liquid crystals includes a phase change (PC) mode, atwisted nematic (TN) mode, a super twisted nematic (STN) mode, anelectrically controlled birefringence (ECB) mode, an opticallycompensated bend (OCB) mode, an in-plane switching (IPS) mode, avertical alignment (VA) mode and a polymer sustained alignment (PSA)mode. A classification based on a driving mode in the device includes apassive matrix (PM) and an active matrix (AM). The PM is classified intostatic, multiplex and so forth, and the AM is classified into a thinfilm transistor (TFT), a metal insulator metal (MIM) and so forth. TheTFT is further classified into amorphous silicon and polycrystalsilicon. The latter is classified into a high temperature type and a lowtemperature type according to a production process. A classificationbased on a light source includes a reflective type utilizing naturallight, a transmissive type utilizing backlight and a transflective typeutilizing both the natural light and the backlight.

The devices include a liquid crystal composition having suitablecharacteristics. The liquid crystal composition has a nematic phase.General characteristics of the composition should be improved to obtainan AM device having good general characteristics. Table 1 belowsummarizes a relationship of the general characteristics between twoaspects. The general characteristics of the composition will be furtherexplained based on a commercially available AM device. A temperaturerange of the nematic phase relates to a temperature range in which thedevice can be used. A preferred maximum temperature of the nematic phaseis about 70° C. or higher and a preferred minimum temperature of thenematic phase is about −10° C. or lower. Viscosity of the compositionrelates to a response time in the device. A short response time ispreferred for displaying moving images on the device. Accordingly, asmall viscosity in the composition is preferred. A small viscosity at alow temperature is further preferred.

TABLE 1 General Characteristics of Composition and AM Device GeneralCharacteristics General Characteristics of Composition of AM Device Widetemperature range of a nematic Wide usable temperature range phase Smallviscosity ¹⁾ Short response time Suitable optical anisotropy Largecontrast ratio Large positive or negative dielectric Low thresholdvoltage and anisotropy small electric power consumption Large contrastratio Large specific resistance Large voltage holding ratio and largecontrast ratio High stability to ultraviolet Long service life light andheat ¹⁾ A liquid crystal composition can be injected into a liquidcrystal cell in a shorter period of time.

An optical anisotropy of the composition relates to a contrast ratio inthe device. A product (Δn×d) of the optical anisotropy (an) of thecomposition and a cell gap (d) in the device is designed so as tomaximize the contrast ratio. A suitable value of the product depends ona type of operating mode. The suitable value is in the range of about0.30 micrometer to about 0.40 micrometer in a device having the VA modeor the PSA mode, and in the range of about 0.20 micrometer to about 0.30micrometer in a device having the IPS mode. In the above case, acomposition having a large optical anisotropy is preferred for a devicehaving a small cell gap. A large absolute value of dielectric anisotropyin the composition contributes to a low threshold voltage, a smallelectric power consumption and a large contrast ratio in the device.Accordingly, the large absolute value of dielectric anisotropy ispreferred. A large specific resistance in the composition contributes toa large voltage holding ratio and a large contrast ratio in the device.Accordingly, a composition having a large specific resistance at roomtemperature and also at a high temperature in an initial stage ispreferred. A composition having a large specific resistance at roomtemperature and also at a high temperature even after the device hasbeen used for a long period of time is preferred. Stability of thecomposition to ultraviolet light and heat relates to a service life ofthe liquid crystal display device. In the case where the stability ishigh, the device has a long service life. Such characteristics arepreferred for an AM device used in a liquid crystal projector, a liquidcrystal television and so forth.

A composition having a positive dielectric anisotropy is used in an AMdevice having the TN mode. On the other hand, a composition having anegative dielectric anisotropy is used in an AM device having the VAmode. A composition having a positive or negative dielectric anisotropyis used in an AM device having the IPS mode. A composition having apositive or negative dielectric anisotropy is used in an AM devicehaving the PSA mode. Examples of the liquid crystal composition havingthe negative dielectric anisotropy are disclosed in Patent literaturesNo. 1 to No. 5 as described below and so forth.

REFERENCE LIST Patent Literature

-   Patent literature No. 1: JP 2004-131704 A.-   Patent literature No. 2: JP 2009-102639 A.-   Patent literature No. 3: WO 2009/030318 A.-   Patent literature No. 4: WO 2009/030322 A.-   Patent literature No. 5: CN 101045866 A.

A desirable AM device has characteristics such as a wide temperaturerange in which a device can be used, a short response time, a largecontrast ratio, a low threshold voltage, a large voltage holding ratioand a long service life. A shorter response time even by one millisecondis desirable. Thus, desirable characteristics of a composition include ahigh maximum temperature of a nematic phase, a low minimum temperatureof the nematic phase, a small viscosity, a suitable optical anisotropy,a large positive or negative dielectric anisotropy, a large specificresistance, a high stability to ultraviolet light and a high stabilityto heat.

In a display having a PSA mode, a small amount (about 0.3% by weight,typically, less than about 1% by weight, for example) of a polymerizablecompound (RM) is added to a liquid crystal composition. Afterintroduction into a liquid crystal display cell, only the polymerizablecompound is polymerized ordinarily under irradiation with ultravioletlight in a state in which a voltage is applied between electrodes toform a polymer structure within the device. As the RM, a polymerizablemesogenic compound or a polymerizable liquid crystal compound is knownto be particularly suitable as a monomer to be added to the liquidcrystal composition.

SUMMARY OF INVENTION Technical Problem

In general, the polymerizable mesogenic compound or the polymerizableliquid crystal compound as described above has a high capability foraligning liquid crystal molecules. On the other hand, the compound has apoor solubility in a liquid crystal composition, and cannot be added ina large amount. In order to prevent crystallization duringtransportation or in a liquid crystal display device, a polymerizablecompound having a high solubility in the liquid crystal composition isdesirable.

One of the aims of the invention is to provide a liquid crystalcomposition satisfying at least one of characteristics such as a highmaximum temperature of a nematic phase, a low minimum temperature of thenematic phase, a small viscosity, a suitable optical anisotropy, a largenegative dielectric anisotropy, a large specific resistance, a highstability to ultraviolet light and a high stability to heat. Another aimis to provide a liquid crystal composition having a suitable balanceregarding at least two of the characteristics. A further aim is toprovide a liquid crystal display device including such a composition. Anadditional aim is to provide a composition having a suitable opticalanisotropy to be a small optical anisotropy or a large opticalanisotropy, a large negative dielectric anisotropy, a high stability toultraviolet light and so forth, and is to provide an AM device having ashort response time, a large voltage holding ratio, a large contrastratio, a long service life and so forth.

Solution to Problem

The invention concerns a liquid crystal composition containing at leastone compound selected from the group of compounds represented by formula(1) as a first component, and a liquid crystal display device includingthe composition:

wherein R¹ is hydrogen or alkyl having 1 to 20 carbons, and in thealkyl, arbitrary —CH₂— may be replaced by —O—, —CH═CH— or —C≡C—; R² andR³ are hydrogen or methyl; A¹ is a single bond, 1,4-phenylene or1,4-cyclohexylene; Z¹ is a single bond or alkylene having 1 to 3carbons; Z² is —O— or alkylene having 1 to 6 carbons; Z³ is a singlebond or —O—; Z⁴ is a single bond or alkylene having 2 to 20 carbons, andin the alkylene, arbitrary —CH₂— may be replaced by —O—; X¹ is hydrogen,halogen, alkyl having 1 to 3 carbons or fluoroalkyl having 1 to 3carbons; a is 0 or 1; and in the formula, arbitrary hydrogen on anarbitrary phenylene ring may be replaced by methyl, cyclohexyl orhalogen.

Advantageous Effects of Invention

An advantage of the invention is a high solubility of a polymerizablecompound in a liquid crystal composition.

Another advantage of the invention is a liquid crystal compositionsatisfying at least one of characteristics such as a high maximumtemperature of a nematic phase, a low minimum temperature of the nematicphase, a small viscosity, a suitable optical anisotropy, a largenegative dielectric anisotropy, a large specific resistance, a highstability to ultraviolet light and a high stability to heat. One aspectof the invention is a liquid crystal composition having a suitablebalance regarding at least two of the characteristics. Another aspect isa liquid crystal display device including such a composition. A furtheraspect is a polymerizable compound having a high solubility, acomposition having a suitable optical anisotropy, a large negativedielectric anisotropy, a high stability to ultraviolet light and soforth, and an AM device having a short response time, a large voltageholding ratio, a large contrast ratio, a long service life and so forth.

DESCRIPTION OF EMBODIMENTS

Usage of terms herein is as described below. A liquid crystalcomposition or a liquid crystal display device of the invention may beabbreviated as “composition” or “device,” respectively. The liquidcrystal display device is a generic term for a liquid crystal displaypanel and a liquid crystal display module. “Liquid crystal compound”means a compound having a liquid crystal phase such as a nematic phaseor a smectic phase, or a compound having no liquid crystal phase butbeing useful as a component of the composition. Such a useful compoundhas a six-membered ring such as 1,4-cyclohexylene and 1,4-phenylene, anda rod-like molecular structure. An optically active compound and apolymerizable compound may occasionally be added to the composition.Even in the case where the compounds are liquid crystalline, thecompounds are classified as an additive herein. At least one compoundselected from the group of compounds represented by formula (1) may beabbreviated as “compound (1).” “Compound (1)” means one compound or twoor more compounds represented by formula (1). A same rule also appliesto any other compound represented by any other formula. “Arbitrary”means a free selection of not only positions but also numbers.

A higher limit of a temperature range of the nematic phase may beabbreviated as “maximum temperature.” A lower limit of the temperaturerange of the nematic phase may be abbreviated as “minimum temperature.”An expression “having a large specific resistance” means that thecomposition has a large specific resistance at room temperature and alsoat a temperature close to the maximum temperature of the nematic phasein an initial stage, and that the composition has a large specificresistance at room temperature and also at a temperature close to themaximum temperature of the nematic phase even after the device has beenused for a long period of time. An expression “having a large voltageholding ratio” means that the device has a large voltage holding ratioat room temperature and also at a temperature close to the maximumtemperature of the nematic phase in an initial stage, and that thedevice has a large voltage holding ratio at room temperature and also ata temperature close to the maximum temperature of the nematic phase evenafter the device has been used for a long period of time. Whencharacteristics such as an optical anisotropy are explained, valuesobtained according to the measuring methods described in Examples willbe used. A first component includes one compound or two or morecompounds. “Ratio of the first component” is expressed in terms of aweight ratio (part by weight) of the first component based on 100 partsby weight of a liquid crystal composition excluding the first component.“Ratio of a second component” means weight percent (% by weight) of thesecond component based on the weight of the liquid crystal compositionexcluding the first component. “Ratio of a third component” is expressedin a manner similar to “ratio of the second component.” A ratio of theadditive mixed with the composition is expressed in terms of weightpercent (% by weight) or weight parts per million (ppm) based on thetotal weight of the liquid crystal composition.

A symbol R¹¹ is used for a plurality of compounds in chemical formulasof component compounds. In two of arbitrary compounds among theplurality of compounds, a group selected by R¹¹ may be identical ordifferent. In one case, for example, R¹¹ of compound (2-1) is ethyl andR¹¹ of compound (2-2) is ethyl. In another case, R¹¹ of compound (2-1)is ethyl and R¹¹ of compound (2-2) is propyl. A same rule also appliesto a symbol R¹², Z¹¹ or the like.

The invention includes the items described below.

Item 1. A liquid crystal composition containing at least one compoundselected from the group of compounds represented by formula (1) as afirst component:

wherein R¹ is hydrogen or alkyl having 1 to 20 carbons, and in thealkyl, arbitrary —CH₂— may be replaced by —O—, —CH═CH— or —C≡C—; R² andR³ are hydrogen or methyl; A¹ is a single bond, 1,4-phenylene or1,4-cyclohexylene; Z¹ is a single bond or alkylene having 1 to 3carbons; Z² is —O— or alkylene having 1 to 6 carbons; Z³ is a singlebond or —O—; Z⁴ is a single bond or alkylene having 2 to 20 carbons, andin the alkylene, arbitrary —CH₂— may be replaced by —O—; X¹ is hydrogen,halogen, alkyl having 1 to 3 carbons or fluoroalkyl having 1 to 3carbons; a is 0 or 1; and in the formula, arbitrary hydrogen on anarbitrary phenylene ring may be replaced by methyl, cyclohexyl orhalogen.Item 2. The liquid crystal composition according to item 1, wherein A¹is a single bond or 1,4-cyclohexylene, a is 0 and X¹ is hydrogen oralkyl having 1 to 3 carbons.Item 3. The liquid crystal composition according to item 1 or 2, whereina ratio of the first component is in the range of 0.05 part by weight to10 parts by weight based on 100 parts by weight of a liquid crystalcomposition excluding the first component.Item 4. The liquid crystal composition according to any one of items 1to 3, further containing at least one compound selected from the groupof compounds represented by formula (2) as a second component:

wherein R¹¹ and R¹² are independently alkyl having 1 to 12 carbons,alkoxy having 1 to 12 carbons or alkenyl having 2 to 12 carbons, oralkenyl having 2 to 12 carbons in which arbitrary hydrogen is replacedby fluorine; ring B and ring D are independently 1,4-cyclohexylene,1,4-phenylene, 1,4-phenylene in which arbitrary hydrogen is replaced byfluorine or chlorine, or tetrahydropyran-2,5-diyl; ring C is2,3-difluoro-1,4-phenylene, 2-chloro-3-fluoro-1,4-phenylene,2,3-difluoro-5-methyl-1,4-phenylene, 3,4,5-trifluoronaphthalene-2,6-diylor 7,8-difluorochroman-2,6-diyl; Z¹¹ and Z¹² are independently a singlebond, ethylene, methyleneoxy or carbonyloxy; and m is 1, 2 or 3, n is 0or 1, and a sum of m and n is 3 or less.Item 5. The liquid crystal composition according to item 4, wherein thesecond component is at least one compound selected from the group ofcompounds represented by formula (2-1) to formula (2-23):

wherein R¹¹ and R¹² are independently alkyl having 1 to 12 carbons,alkoxy having 1 to 12 carbons or alkenyl having 2 to 12 carbons, oralkenyl having 2 to 12 carbons in which arbitrary hydrogen is replacedby fluorine.Item 6. The liquid crystal composition according to item 5, wherein thesecond component is at least one compound selected from the group ofcompounds represented by formula (2-1).Item 7. The liquid crystal composition according to item 5, wherein thesecond component is a mixture of at least one compound selected from thegroup of compounds represented by formula (2-1) and at least onecompound selected from the group of compounds represented by formula(2-3).Item 8. The liquid crystal composition according to item 5, wherein thesecond component is a mixture of at least one compound selected from thegroup of compounds represented by formula (2-1) and at least onecompound selected from the group of compounds represented by formula(2-5).Item 9. The liquid crystal composition according to item 5, wherein thesecond component is at least one compound selected from the group ofcompounds represented by formula (2-22).Item 10. The liquid crystal composition according to any one of items 4to 9, wherein a ratio of the second component is in the range of 10% byweight to 90% by weight based on the weight of a liquid crystalcomposition excluding the first component.Item 11. The liquid crystal composition according to any one of items 1to 10, further containing at least one compound selected from the groupof compounds represented by formula (3) as a third component:

wherein R¹³ and R¹⁴ are independently alkyl having 1 to 12 carbons,alkoxy having 1 to 12 carbons or alkenyl having 2 to 12 carbons, oralkenyl having 2 to 12 carbons in which arbitrary hydrogen is replacedby fluorine; ring E and ring F are independently 1,4-cyclohexylene,1,4-phenylene, 2-fluoro-1,4-phenylene or 3-fluoro-1,4-phenylene; Z¹³ isindependently a single bond, ethylene, methyleneoxy or carbonyloxy; andp is 1, 2 or 3.Item 12. The liquid crystal composition according to item 11, whereinthe third component is at least one compound selected from the group ofcompounds represented by formula (3-1) to formula (3-13):

wherein R¹³ and R¹⁴ are independently alkyl having 1 to 12 carbons,alkoxy having 1 to 12 carbons or alkenyl having 2 to 12 carbons, oralkenyl having 2 to 12 carbons in which arbitrary hydrogen is replacedby fluorine.Item 13. The liquid crystal composition according to item 12, whereinthe third component is at least one compound selected from the group ofcompounds represented by formula (3-5).Item 14. The liquid crystal composition according to item 12, whereinthe third component is at least one compound selected from the group ofcompounds represented by formula (3-8).Item 15. The liquid crystal composition according to any one of items 11to 14, wherein a ratio of the third component is in the range of 10% byweight to 90% by weight based on the weight of a liquid crystalcomposition excluding the first component.Item 16. The liquid crystal composition according to any one of items 1to 15, further containing a polymerization initiator.Item 17. The liquid crystal composition according to any one of items 1to 16, further containing a polymerization inhibitor.Item 18. The liquid crystal composition according to any one of items 1to 17, wherein a maximum temperature of a nematic phase is 70° C. orhigher, an optical anisotropy (25° C.) at a wavelength of 589 nanometersis 0.08 or more, and a dielectric anisotropy (25° C.) at a frequency of1 kHz is −2 or less.Item 19. A liquid crystal display device, comprising two substratesincluding an electrode layer on at least one of the substrates, andarranging between the two substrates the liquid crystal compositionaccording to any one of items 1 to 18.Item 20. The liquid crystal display device according to item 19, whereinan operating mode in the liquid crystal display device is a TN mode, aVA mode, an IPS mode or a PSA mode, and a driving mode in the liquidcrystal display device is an active matrix mode.

The invention further includes the following items: (1) the composition,further containing the optically active compound; (2) the composition,further containing the additive such as an antioxidant, an ultravioletlight absorber or an antifoaming agent; (3) an AM device including thecomposition; (4) a device including the composition, and having a TN, anECB, an OCB, an IPS, a VA or a PSA mode; (5) a transmissive deviceincluding the composition; (6) use of the composition as the compositionhaving the nematic phase; and (7) use as an optically active compositionby adding the optically active compound to the composition.

The composition of the invention will be explained in the followingorder. First, a constitution of the component compounds in thecomposition will be explained. Second, main characteristics of thecomponent compounds and main effects of the compounds on the compositionwill be explained. Third, a combination of components in thecomposition, a preferred ratio of the component compounds and the basisthereof will be explained. Fourth, a preferred embodiment of thecomponent compounds will be explained. Fifth, specific examples of thecomponent compounds will be shown. Sixth, the additive that may be mixedwith the composition will be explained. Seventh, methods forsynthesizing the component compounds will be explained. Last, anapplication of the composition will be explained.

First, the constitution of the component compounds in the compositionwill be explained. The composition of the invention is classified intocomposition A and composition B. Composition A may further contain anyother liquid crystal compound, the additive and an impurity. “Any otherliquid crystal compound” means a liquid crystal compound different fromcompound (1), compound (2) and compound (3). Such a compound is mixedwith the composition for the purpose of further adjusting thecharacteristics. Of any other liquid crystal compounds, a ratio of acyano compound is preferably as small as possible in view of stabilityto heat or ultraviolet light. A further preferred ratio of the cyanocompound is 0% by weight. The additive includes the optically activecompound, the antioxidant, the ultraviolet light absorber, a dye, theantifoaming agent, the polymerizable compound and the polymerizationinitiator. The impurity includes a compound mixed in a process such aspreparation of the component compounds. Even in the case where thecompound is liquid crystalline, the compound is classified as theimpurity herein.

Composition B consists essentially of compound (1), compound (2) andcompound (3). A term “essentially” means that the composition maycontain the additive and the impurity, but does not contain any liquidcrystal compound different from the compounds. Composition B has asmaller number of components than composition A has. Composition B ispreferred to composition A in view of cost reduction. Composition A ispreferred to composition B in view of possibility of further adjustingphysical properties by mixing any other liquid crystal compound.

Second, the main characteristics of the component compounds and the maineffects of the compounds on the characteristics of the composition willbe explained. The main characteristics of the component compounds aresummarized in Table 2 on the basis of advantageous effects of theinvention. In Table 2, a symbol L stands for “large” or “high,” a symbolM stands for “medium,” and a symbol S stands for “small” or “low.” Thesymbols L, M and S represent a classification based on a qualitativecomparison among the component compounds, and 0 (zero) means “a value isclose to zero.”

TABLE 2 Characteristics of Compounds Compounds Compound (2) Compound (3)Maximum temperature S to L S to L Viscosity M to L S to M Opticalanisotropy M to L S to L Dielectric anisotropy M to L ¹⁾ 0 Specificresistance L L ¹⁾ A value of dielectric anisotropy is negative, and thesymbol shows magnitude of an absolute value.

Upon mixing the component compounds with the composition, the maineffects of the component compounds on the characteristics of thecomposition are as described below. Compound (2) increases the absolutevalue of dielectric anisotropy and decreases the minimum temperature.Compound (3) decreases the viscosity or increases the maximumtemperature.

Third, the combination of components in the composition, the preferredratio of the components and the basis thereof will be explained. Thecombination of components in the composition includes a combination ofthe first component and the second component, a combination of the firstcomponent and the third component, and a combination of the firstcomponent, the second component and the third component.

A preferred ratio of the first component is about 0.05 part by weight ormore for achieving the effect thereof, and about 10 parts by weight orless for avoiding a poor display, based on 100 parts by weight of theliquid crystal composition excluding the first component. A furtherpreferred ratio is in the range of about 0.1 part by weight to about 2parts by weight.

A preferred ratio of the second component is about 10% by weight or morefor increasing the absolute value of dielectric anisotropy, and about90% by weight or less for decreasing the minimum temperature, based onthe liquid crystal composition excluding the first component. A furtherpreferred ratio is in the range of about 20% by weight to about 80% byweight. A particularly preferred ratio is in the range of about 30% byweight to about 70% by weight.

A preferred ratio of the third component is about 10% by weight or morefor decreasing the viscosity or increasing the maximum temperature, andabout 90% or less for increasing the absolute value of dielectricanisotropy, based on the liquid crystal composition excluding the firstcomponent. A further preferred ratio is in the range of about 20% byweight to about 80% by weight. A particularly preferred ratio is in therange of about 30% by weight to about 70% by weight.

Fourth, the preferred embodiment of the component compounds will beexplained. R¹ is hydrogen or alkyl having 1 to 20 carbons, and in thealkyl, arbitrary —CH₂— may be replaced by —O—, —CH═CH— or —C≡C—.Preferred R¹ is hydrogen or alkyl having 1 to 20 carbons. R² and R³ arehydrogen or methyl. Preferred R² and R³ are hydrogen. R¹¹, R¹², R¹³ andR¹⁴ are independently alkyl having 1 to 12 carbons, alkoxy having 1 to12 carbons or alkenyl having 2 to 12 carbons, or alkenyl having 2 to 12carbons in which arbitrary hydrogen is replaced by fluorine. PreferredR¹¹ or R¹² is alkyl having 1 to 12 carbons for increasing the stabilityto ultraviolet light, or the like, or increasing the stability to heat,and alkoxy having 1 to 12 carbons for increasing the absolute value ofdielectric anisotropy. Preferred R¹³ or R¹⁴ is alkyl having 1 to 12carbons for increasing the stability to ultraviolet light or thestability to heat, and alkenyl having 2 to 12 carbons for decreasing theminimum temperature.

Preferred alkyl is methyl, ethyl, propyl, butyl, pentyl, hexyl, heptylor octyl. Further preferred alkyl is ethyl, propyl, butyl, pentyl orheptyl for decreasing the viscosity.

Preferred alkylene is methylene, ethylene, propylene, butylene,pentylene, hexylene, heptylene or octylene. Further preferred alkyleneis methylene, ethylene, butylene, pentylene or heptylene for decreasingthe viscosity.

Preferred alkoxy is methoxy, ethoxy, propoxy, butoxy, pentyloxy,hexyloxy or heptyloxy. Further preferred alkoxy is methoxy or ethoxy fordecreasing the viscosity.

Preferred alkenyl is vinyl, 1-propenyl, 2-propenyl, 1-butenyl,2-butenyl, 3-butenyl, 1-pentenyl, 2-pentenyl, 3-pentenyl, 4-pentenyl,1-hexenyl, 2-hexenyl, 3-hexenyl, 4-hexenyl or 5-hexenyl. Furtherpreferred alkenyl is vinyl, 1-propenyl, 3-butenyl or 3-pentenyl fordecreasing the viscosity. A preferred configuration of —CH═CH— in thealkenyl depends on a position of a double bond. Trans is preferred inthe alkenyl such as 1-propenyl, 1-butenyl, 1-pentenyl, 1-hexenyl,3-pentenyl and 3-hexenyl for decreasing the viscosity, for instance. Cisis preferred in the alkenyl such as 2-butenyl, 2-pentenyl and 2-hexenyl.In the alkenyl, straight-chain alkenyl is preferred to branched-chainalkenyl.

Preferred examples of alkenyl in which arbitrary hydrogen is replaced byfluorine include 2,2-difluorovinyl, 3,3-difluoro-2-propenyl,4,4-difluoro-3-butenyl, 5,5-difluoro-4-pentenyl and6,6-difluoro-5-hexenyl. Further preferred examples include2,2-difluorovinyl and 4,4-difluoro-3-butenyl for decreasing theviscosity.

A¹ is a single bond, 1,4-phenylene or 1,4-cyclohexylene. Preferred A¹ isa single bond or 1,4-cyclohexylene. Ring B and ring D are independently1,4-cyclohexylene, 1,4-phenylene, 1,4-phenylene in which arbitraryhydrogen is replaced by fluorine or chlorine, ortetrahydropyran-2,5-diyl. Tetrahydropyran-2,5-diyl includes:

preferably,

Ring C is 2,3-difluoro-1,4-phenylene, 2-chloro-3-fluoro-1,4-phenylene,2,3-difluoro-5-methyl-1,4-phenylene, 3,4,5-trifluoronaphthalene-2,6-diylor 7,8-difluorochroman-2,6-diyl. Two of arbitrary ring B when m is 2 or3 may be identical or different. Preferred ring B or ring D is1,4-cyclohexylene for decreasing the viscosity. Preferred ring C is2,3-difluoro-1,4-phenylene for decreasing the viscosity and increasingthe absolute value of dielectric anisotropy. Ring E and ring F areindependently 1,4-cyclohexylene, 1,4-phenylene, 2-fluoro-1,4-phenyleneor 3-fluoro-1,4-phenylene, and two of arbitrary ring E when p is 2 or 3may be identical or different. Preferred ring E or ring F is1,4-cyclohexylene for decreasing the viscosity, and 1,4-phenylene forincreasing the optical anisotropy.

Z¹ is a single bond or alkylene having 1 to 3 carbons. Preferred Z¹ is asingle bond.

Z² is —O— or alkylene having 1 to 6 carbons. Preferred Z² is alkylenehaving 1 to 6 carbons. Z³ is a single bond or —O—. Preferred Z³ is asingle bond. Z⁴ is a single bond or alkylene having 2 to 20 carbons, andin the alkylene, arbitrary —CH₂— may be replaced by —O—. Preferred Z⁴ isa single bond. X¹ is hydrogen, halogen, alkyl having 1 to 3 carbons orfluoroalkyl having 1 to 3 carbons. Preferred X¹ is alkyl having 1 to 3carbons. Z¹¹ is independently hydrogen, fluorine, chlorine, methyl or—CF₃. Preferred Z¹¹ is hydrogen or methyl. Z¹², Z¹³ and Z¹⁴ areindependently a single bond, ethylene, methyleneoxy or carbonyloxy, twoof arbitrary Z¹² when m is 2 or 3 may be identical or different, and twoof arbitrary Z¹⁴ when p is 2 or 3 may be identical or different.Preferred Z¹² or Z¹³ is a single bond for decreasing the viscosity, andmethyleneoxy for increasing the absolute value of dielectric anisotropy.Preferred Z¹⁴ is a single bond for decreasing the viscosity.

Then, a is 0 or 1. Preferred a is 0. Herein, m is 1, 2 or 3, n is 0 or1, and a sum of m and n is 3 or less. Preferred m is 1 for decreasingthe minimum temperature. Preferred n is 0 for decreasing the viscosity.Moreover, p is 1, 2 or 3. Preferred p is 1 for decreasing the viscosity,and 3 for increasing the maximum temperature. Furthermore, j and q arean integer from 0 to 10, k and r are 0 or 1, k when j is 0 is 0, and rwhen q is 0 is 0. Preferred j or q is 2 for increasing photoreactivity,and 0 for increasing alignment properties. Preferred k or r is 1 forincreasing the photoreactivity, and 0 for increasing the alignmentproperties.

Fifth, the specific examples of the component compounds will be shown.In the preferred compounds described below, R⁴ is alkyl having 1 to 20carbons. R¹⁵ is straight-chain alkyl having 1 to 12 carbons, orstraight-chain alkoxy having 1 to 12 carbons. R¹⁶ and R¹⁷ areindependently straight-chain alkyl having 1 to 12 carbons orstraight-chain alkenyl having 2 to 12 carbons. With regard to aconfiguration of 1,4-cyclohexylene in the compounds, trans is preferredto cis for increasing the maximum temperature.

Preferred compound (1) includes compound (1-1) and compound (1-2).Preferred compound (2) includes compound (2-1-1) to compound (2-23-1).Further preferred compound (2) includes compound (2-1-1) to compound(2-3-1), compound (2-5-1), compound (2-8-1), compound (2-11-1), compound(2-13-1) and compound (2-22-1). Particularly preferred compound (2)includes compound (2-1-1), compound (2-3-1), compound (2-5-1) andcompound (2-22-1). Preferred compound (3) includes compound (3-1-1) tocompound (3-13-1). Further preferred compound (3) includes compound(3-1-1), compound (3-5-1), compound (3-8-1), compound (3-9-1) andcompound (3-10-1). Particularly preferred compound (3) includes compound(3-1-1), compound (3-5-1) and compound (3-8-1).

Sixth, the additive that may be mixed with the composition will beexplained. Such an additive includes the optically active compound, theantioxidant, the ultraviolet light absorber, the dye, the antifoamingagent, the polymerization initiator and the polymerization inhibitor.The optically active compound is mixed with the composition for thepurpose of inducing a helical structure in liquid crystals to give atwist angle. Examples of such a compound include compound (4-1) tocompound (4-4). A preferred ratio of the optically active compound isabout 5% by weight or less. A further preferred ratio is in the range ofabout 0.01% by weight to about 2% by weight.

The antioxidant is mixed with the composition for the purpose ofpreventing a decrease in the specific resistance caused by heating inair, or maintaining a large voltage holding ratio at room temperatureand also at a temperature close to the maximum temperature of thenematic phase even after the device has been used for a long period oftime.

Preferred examples of the antioxidant include compound (5) where is aninteger from 1 to 9. In compound (5), preferred s is 1, 3, 5, 7 or 9.Further preferred s is 1 or 7. Compound (5) where s is 1 is effective inpreventing a decrease in the specific resistance caused by heating inair because the compound (5) has a large volatility. Compound (5) wheres is 7 is effective in maintaining a large voltage holding ratio at roomtemperature and also at a temperature close to the maximum temperatureof the nematic phase even after the device has been used fora longperiod of time because the compound (5) has a small volatility. Apreferred ratio of the antioxidant is about 50 ppm or more for achievingthe effect thereof, and about 600 ppm or less for avoiding a decrease inthe maximum temperature or avoiding an increase in the minimumtemperature. A further preferred ratio is in the range of about 100 ppmto about 300 ppm.

Preferred examples of the ultraviolet light absorber include abenzophenone derivative, a benzoate derivative and a triazolederivative. A light stabilizer such as an amine having steric hindranceis also preferred. A preferred ratio of the ultraviolet light absorberor the stabilizer is about 50 ppm or more for achieving the effectthereof, and about 10,000 ppm or less for avoiding a decrease in themaximum temperature or avoiding an increase in the minimum temperature.A further preferred ratio is in the range of about 100 ppm to about10,000 ppm.

A dichroic dye such as an azo dye or an anthraquinone dye is mixed withthe composition to be adapted for a device having a guest host (GH)mode. A preferred ratio of the dye is in the range of about 0.01% byweight to about 10% by weight.

The antifoaming agent such as dimethyl silicone oil or methyl phenylsilicone oil is mixed with the composition for preventing foamformation. A preferred ratio of the antifoaming agent is about 1 ppm ormore for achieving the effect thereof, and about 1,000 ppm or less foravoiding a poor display. A further preferred ratio is in the range ofabout 1 ppm to about 500 ppm.

The polymerizable compound is mixed with the composition to be adaptedfor the device having the polymer sustained alignment (PSA) mode.Preferred examples of the polymerizable compound include a compoundhaving a polymerizable group, such as an acrylate, a methacrylate, avinyl compound, a vinyloxy compound, a propenyl ether, an epoxy compound(oxirane, oxetane) and a vinyl ketone. Particularly preferred examplesinclude an acrylate derivative or a methacrylate derivative. A preferredratio of the polymerizable compound is about 0.05% by weight or more forachieving the effect thereof, and about 10% by weight or less foravoiding a poor display. A further preferred ratio is in the range ofabout 0.1% by weight to about 2% by weight. The polymerizable compoundis preferably polymerized by irradiation with ultraviolet light or thelike in the presence of a suitable initiator such as aphotopolymerization initiator. Suitable conditions for polymerization,suitable types of the initiator and suitable amounts thereof are knownto those skilled in the art and are described in literatures. Forexample, Irgacure 651 (registered trademark), Irgacure 184 (registeredtrademark) or Darocure 1173 (registered trademark) (Ciba Japan K. K.),each being a photoinitiator, is suitable for radical polymerization. Thepolymerizable compound contains the photopolymerization initiatorpreferably in the range of about 0.1% by weight to about 5% by weight,particularly preferably, in the range of about 1% by weight to about 3%by weight. A polymerized compound may be arranged through a process ofarranging the liquid crystal composition containing the polymerizablecompound between two substrates in the liquid crystal display device andpolymerizing the polymerizable compound while applying a voltage betweenopposing electrode layers on the substrates, or a liquid crystalcomposition containing a preliminarily polymerized compound may bearranged between the two substrates in the liquid crystal displaydevice.

Seventh, the methods for synthesizing the component compounds will beexplained. The compounds can be prepared according to known methods.Examples of synthetic methods will be shown. Compound (1-2) is preparedby the method described in JP S63-215653 A (1988). Compound (2-1-1) isprepared by the method described in JP 2000-053602 A (2000). Compound(3-1-1) and compound (3-5-1) are prepared by the method described in JPS59-176221 A (1984). The antioxidant is commercially available. Acompound represented by formula (5) where s is 1 is available fromSigma-Aldrich Corporation. Compound (5) where s is 7 and so forth areprepared according to the method described in U.S. Pat. No. 3,660,505 B.

Any compounds whose synthetic methods are not described above can beprepared according to the methods described in books such as OrganicSyntheses (John Wiley & Sons, Inc.), Organic Reactions (John Wiley &Sons, Inc.), Comprehensive Organic Synthesis (Pergamon Press) and NewExperimental Chemistry Course (Shin Jikken Kagaku Koza in Japanese)(Maruzen Co., Ltd.). The composition is prepared according to publiclyknown methods using the thus obtained compounds. For example, thecomponent compounds are mixed and dissolved in each other by heating.

Last, the application of the composition will be explained. Most of thecompositions have a minimum temperature of about −10° C. or lower, amaximum temperature of about 70° C. or higher, and an optical anisotropyin the range of about 0.07 to about 0.20. The device including thecomposition has a large voltage holding ratio. The composition issuitable for use in the AM device. The composition is particularlysuitable for use in a transmissive AM device. The composition having anoptical anisotropy in the range of about 0.08 to about 0.25 may beprepared by controlling the ratio of the component compounds or bymixing with any other liquid crystal compound. The composition can beused as the composition having the nematic phase and as the opticallyactive composition by adding the optically active compound.

The composition can be used in the AM device. The composition can alsobe used in a PM device. The composition can also be used in an AM deviceand a PM device both having a mode such as PC, TN, STN, ECB, OCB, IPS,VA or PSA. Use for in the AM device having the PSA mode is particularlypreferred. The devices may be of a reflective type, a transmissive typeor a transflective type. Use for in the transmissive device ispreferred. The composition can also be used in an amorphous silicon-TFTdevice or a polycrystal silicon-TFT device. The composition can also beused in a nematic curvilinear aligned phase (NCAP) device prepared bymicroencapsulating the composition, and in a polymer dispersed (PD)device in which a three-dimensional network polymer is formed in thecomposition.

The liquid crystal display device of the invention is characterized bycomprising two substrates including the electrode layer on at least oneof the substrates, and arranging between the two substrates the liquidcrystal composition of the invention or the liquid crystal compositioncontaining the compound formed by polymerizing the compound of theinvention. For example, the liquid crystal display device comprises twoglass substrates referred to as an array substrate and a color filtersubstrate, and a thin film transistor (TFT), pixels, a coloring layerand so forth are formed on each of the glass substrates. Analuminosilicate glass or aluminoborosilicate glass is used for the glasssubstrates, for example. For the electrode layer, Indium-Tin Oxide andIndium-Zinc Oxide are generally used.

EXAMPLES

In order to evaluate characteristics of a composition and a compound tobe contained in the composition, the composition and the compound weremade a measurement object. When the measurement object was thecomposition, the composition was measured as a sample as is, and valuesobtained were described. When the measurement object was the compound, asample for measurement was prepared by mixing the compound (15% byweight) with mother liquid crystals (85% by weight). Values ofcharacteristics of the compound were calculated using values obtained bymeasurement, according to an extrapolation method: (extrapolatedvalue)={(measured value of a sample for measurement)−0.85×(measuredvalue of mother liquid crystals)}/0.15. When a smectic phase (orcrystals) precipitated at the above ratio at 25° C., a ratio of thecompound to the mother liquid crystals was changed step by step in theorder of (10% by weight:90% by weight), (5% by weight:95% by weight) and(1% by weight:99% by weight). Values of a maximum temperature, anoptical anisotropy, viscosity and a dielectric anisotropy with regard tothe compound were determined according to the extrapolation method.

Components of the mother liquid crystals and ratios thereof were asdescribed below.

The characteristics were measured according to the methods describedbelow. Most of the methods are applied as described in EIAJ ED-2521A ofthe Standard of Electronic Industries Association of Japan, or asmodified thereon.

Maximum Temperature of a Nematic Phase (NI; ° C.):

A sample was placed on a hot plate in a melting point apparatus equippedwith a polarizing microscope and was heated at a rate of 1° C. perminute. Temperature when a part of the sample began to change from anematic phase to an isotropic liquid was measured. A higher limit of atemperature range of the nematic phase may be abbreviated as “maximumtemperature.”

Minimum Temperature of a Nematic Phase (T_(c); ° C.):

A sample having a nematic phase was put in glass vials and kept infreezers at temperatures of 0° C., −10° C., −20° C., −30° C. and −40° C.for 10 days, and then liquid crystal phases were observed. For example,when the sample maintained the nematic phase at −20° C. and changed tocrystals or a smectic phase at −30° C., T_(c) was expressed asT_(c)≦−20° C. A lower limit of the temperature range of the nematicphase may be abbreviated as “minimum temperature.”

Viscosity (Bulk Viscosity; η; Measured at 20° C.; mPa·s):

A cone-plate (E type) rotational viscometer was used for measurement.

Optical Anisotropy (Refractive Index Anisotropy; Δn; Measured at 25°C.):

Measurement was carried out by means of an Abbe refractometer with apolarizing plate mounted on an ocular, using light at a wavelength of589 nanometers. A surface of a main prism was rubbed in one direction,and then a sample was added dropwise onto the main prism. A refractiveindex (nib) was measured when the direction of polarized light wasparallel to the direction of rubbing. A refractive index (n⊥) wasmeasured when the direction of polarized light was perpendicular to thedirection of rubbing. A value of optical anisotropy was calculated froman equation: Δn=n∥−n⊥.

Dielectric Anisotropy (Δ∈; Measured at 25° C.):

A value of dielectric anisotropy was calculated from an equation:Δ∈=∈∥−∈⊥. A dielectric constant (∈∥ and ∈⊥) was measured as describedbelow.

(1) Measurement of dielectric constant (∈∥): An ethanol (20 mL) solutionof octadecyl triethoxysilane (0.16 mL) was applied to a well-washedglass substrate. After rotating the glass substrate with a spinner, theglass substrate was heated at 150° C. for 1 hour. A sample was put in aVA device in which a distance (cell gap) between two glass substrateswas 4 micrometers, and the device was sealed with an ultraviolet-curableadhesive. Sine waves (0.5 V, 1 kHz) were applied to the device, andafter 2 seconds, a dielectric constant (∈∥) in the major axis directionof liquid crystal molecules was measured.

(2) Measurement of dielectric constant (∈⊥): A polyimide solution wasapplied to a well-washed glass substrate. After calcining the glasssubstrate, rubbing treatment was applied to the alignment film obtained.A sample was put in a TN device in which a distance (cell gap) betweentwo glass substrates was 9 micrometers and a twist angle was 80 degrees.Sine waves (0.5 V, 1 kHz) were applied to the device, and after 2seconds, a dielectric constant (∈⊥) in the minor axis direction of theliquid crystal molecules was measured.

Threshold Voltage (Vth; Measured at 25° C.; V):

An LCD-5100 luminance meter made by Otsuka Electronics Co., Ltd. wasused for measurement. Alight source was a halogen lamp. A sample was putin a normally black mode VA device in which a distance (cell gap)between two glass substrates was 4 micrometers and a rubbing directionwas anti-parallel, and the device was sealed with an ultraviolet-curableadhesive. A voltage (60 Hz, rectangular waves) to be applied to thedevice was stepwise increased from 0 V to 20 V at an increment of 0.02V. On the occasion, the device was irradiated with light from adirection perpendicular to the device, and the amount of lighttransmitting the device was measured. A voltage-transmittance curve wasprepared, in which the maximum amount of light corresponds to 100%transmittance and the minimum amount of light corresponds to 0%transmittance. A threshold voltage is a voltage at 10% transmittance.

Voltage Holding Ratio (VHR-1; at 25° C.; %):

A TN device used for measurement had a polyimide alignment film, and adistance (cell gap) between two glass substrates was 5 micrometers. Asample was put in the device, and then the device was sealed with anultraviolet-curable adhesive. A pulse voltage (60 microseconds at 5 V)was applied to the TN device and the device was charged. A decayingvoltage was measured for 16.7 milliseconds with a high-speed voltmeter,and area A between a voltage curve and a horizontal axis in a unit cyclewas determined. Area B is an area without decay. A voltage holding ratiois a percentage of area A to area B.

Voltage Holding Ratio (VHR-2; at 80° C.; %):

A TN device used for measurement had a polyimide alignment film, and adistance (cell gap) between two glass substrates was 5 micrometers. Asample was put in the device, and then the device was sealed with anultraviolet-curable adhesive. A pulse voltage (60 microseconds at 5 V)was applied to the TN device and the device was charged. A decayingvoltage was measured for 16.7 milliseconds with a high-speed voltmeter,and area A between a voltage curve and a horizontal axis in a unit cyclewas determined. Area B is an area without decay. A voltage holding ratiois a percentage of area A to area B.

Voltage Holding Ratio (VHR-3; at 25° C.; %):

Stability to ultraviolet light was evaluated by measuring a voltageholding ratio after a device was irradiated with ultraviolet light. A TNdevice used for measurement had a polyimide alignment film, and a cellgap was 5 micrometers. A sample was injected into the device, and thenthe device was irradiated with light for 20 minutes. A light source wasan ultra high-pressure mercury lamp USH-500D (made by Ushio, Inc.), anda distance between the device and the light source was 20 centimeters.In measuring VHR-3, a decaying voltage was measured for 16.7milliseconds. A composition having a large VHR-3 has a large stabilityto ultraviolet light. A value of VHR-3 is preferably 90% or more,further preferably, 95% or more.

Voltage Holding Ratio (VHR-4; at 25° C.; %):

A TN device into which a sample was injected was heated in aconstant-temperature bath at 80° C. for 500 hours, and then stability toheat was evaluated by measuring a voltage holding ratio. In measuringVHR-4, a decaying voltage was measured for 16.7 milliseconds. Acomposition having a large VHR-4 has a large stability to heat.

Response Time (τ; measured at 25° C.; ms): An LCD-5100 luminance metermade by Otsuka Electronics Co., Ltd. was used for measurement. A lightsource was a halogen lamp. A low-pass filter was set at 5 kHz. A samplewas put in a normally black mode PVA device in which a distance (cellgap) between two glass substrates was 3.2 micrometers and a rubbingdirection was anti-parallel, and the device was sealed with anultraviolet-curable adhesive. A voltage a little over a thresholdvoltage was applied to the device for about 1 minute, and then thedevice was irradiated with ultraviolet light of 23.5 mW/cm² for about 8minutes while applying a voltage of 5.6 V to the device. Rectangularwaves (60 Hz, 10 V, 0.5 second) were applied to the device. On theoccasion, the device was irradiated with light from a directionperpendicular to the device, and the amount of light transmitting thedevice was measured. The maximum amount of light corresponds to 100%transmittance, and the minimum amount of light corresponds to 0%transmittance. A response time is a period of time needed for a changefrom 0% transmittance to 90% transmittance (rise time; millisecond).

Specific Resistance (ρ; Measured at 25° C.; Ωcm):

Into a vessel equipped with electrodes, 1.0 milliliter of a sample wasinjected. A DC voltage (10 V) was applied to the vessel, and a DCcurrent after 10 seconds was measured. A specific resistance wascalculated from the following equation: (specificresistance)={(voltage)×(electric capacity of a vessel)}/{(directcurrent)×(dielectric constant of vacuum)}.

Gas Chromatographic Analysis:

GC-14B Gas Chromatograph made by Shimadzu Corporation was used formeasurement. A carrier gas was helium (2 mL per minute). A sampleinjector and a detector (FID) were set to 280° C. and 300° C.,respectively. A capillary column DB-1 (length 30 m, bore 0.32 mm, filmthickness 0.25 μm; dimethylpolysiloxane as a stationary phase,non-polar) made by Agilent Technologies, Inc. was used for separation ofcomponent compounds. After the column was kept at 200° C. for 2 minutes,the column was heated to 280° C. at a rate of 5° C. per minute. A samplewas prepared in an acetone solution (0.1% by weight), and then 1microliter of the solution was injected into the sample injector. Arecorder was C-R5A Chromatopac made by Shimadzu Corporation or theequivalent thereof. The resulting chromatogram showed a retention timeof a peak and a peak area corresponding to each of the componentcompounds.

As a solvent for diluting the sample, chloroform, hexane and so forthmay also be used. The following capillary columns may also be used forseparating the component compounds: HP-1 (length 30 m, bore 0.32 mm,film thickness 0.25 μm) made by Agilent Technologies, Inc., Rtx-1(length 30 m, bore 0.32 mm, film thickness 0.25 μm) made by RestekCorporation and BP-1 (length 30 m, bore 0.32 mm, film thickness 0.25 μm)made by SGE International Pty. Ltd. A capillary column CBP1-M50-025(length 50 m, bore 0.25 mm, film thickness 0.25 μm) made by ShimadzuCorporation may also be used for the purpose of avoiding an overlap ofpeaks of the compounds.

A ratio of liquid crystal compounds contained in the composition may becalculated by the method as described below. The liquid crystalcompounds can be detected by means of a gas chromatograph. A ratio ofpeak areas in the gas chromatogram corresponds to a ratio (in the numberof moles) of liquid crystal compounds. When the capillary columnsdescribed above were used, a correction coefficient of each liquidcrystal compound may be regarded as 1 (one). Accordingly, a ratio (% byweight) of liquid crystal compounds was calculated from the ratio ofpeak areas.

The invention will be explained in detail by way of Examples. Theinvention is not limited by the Examples described below. The compoundsin Comparative Examples and Examples were described using symbolsaccording to definitions in Table 3 below. In Table 3, a configurationof 1,4-cyclohexylene is trans. A parenthesized number next to asymbolized compound in Comparative examples and Examples corresponds tothe number of the compound. A symbol (−) means any other liquid crystalcompound. A ratio (percentage) of the liquid crystal compounds isexpressed in terms of weight percent (% by weight) based on the weightof the liquid crystal composition excluding the first composition. Theliquid crystal composition further includes an impurity in additionthereto. Last, values of characteristics of the composition weresummarized.

TABLE 3 Method for Description of Compounds using SymbolsR—(A₁)—Z₁- - - -Z_(n)—(A_(n))—R′ 1) Left-terminal Group R— SymbolC_(n)H_(2n+1)— n— C_(n)H_(2n+1)O— nO— C_(m)H_(2m+1)OC_(n)H_(2n)— mOn—CH₂═CH— V— C_(n)H_(2n+1)—CH═CH— nV— CH₂═CH—C_(n)H_(2n)— Vn—C_(m)H_(2m+1)—CH═CH—C_(n)H_(2n)— mVn— CF₂═CH— VFF— CF₂═CH—C_(n)H_(2n)—VFFn— CH₂═CHCOO— AC— CH₂═C(CH₃)COO— MAC— 2) Right-terminal Group —Symbol —C_(n)H_(2n+1) —n —OC_(n)H_(2n+1) —On —CH═CH₂ —V—CH═CH—C_(n)H_(2n+1) —Vn —C_(n)H_(2n)—CH═CH₂ —nV —CH═CF₂ —VFF —COOCH₃—EMe —OCOCH═CH₂ —AC —OCOC(CH₃)═CH₂ —MAC 3) Bonding Group —Zn— Symbol—C₂H₄— 2 —COO— E —CH═CH— V —C≡C— T —CF₂O— X —CH₂O— 1O —SiH₂— Si 4) RingStructure —A_(n)— Symbol

H

Dh

B

B(F)

B(2F)

B(2F, 5F)

B(2F, 3F)

B(2F, 3F, 6Me)

B(2F, 3CL)

Np

Cro(7F, 8F)

[HH-1]

[H] 5) Examples of Description Example 1 3-HB(2F, 3F)-O2

Example 2 MAC-B-[HH-5]-B-MAC

Comparative Example 1

Components of liquid crystal composition A and ratios thereof were asdescribed below.

3-H2B(2F,3F)-O2 (2-2-1) 18% 5-H2B(2F,3F)-O2 (2-2-1) 17%3-HH1OCro(7F,8F)-5 (2-22-1) 6% 3-HBB(2F,3F)-O2 (2-5-1) 10%4-HBB(2F,3F)-O2 (2-5-1) 6% 5-HBB(2F,3F)-O2 (2-5-1) 6% 2-HH-3 (3-1-1) 14%3-HH-4 (3-1-1) 8% 3-HHB-1 (3-5-1) 5% 3-HHB-3 (3-5-1) 6% 3-HHB-O1 (3-5-1)4%

When 0.5 part by weight of compound (R-1) having biphenyl as a ringstructure as described below was added to 100 parts by weight of liquidcrystal composition A and dissolution of the compound was attempted bycarrying out stirring at 25° C. for 3 hours, the compound was dissolved.Characteristics of the composition were as described below.

NI=78.8° C.; Tc≦−20° C.; Δn=0.092; Δ∈=−3.5; Vth=2.04 V; τ=5.3 ms;VHR-1=99.2%; VHR-2=97.9%.

Moreover, when 1 part by weight of compound (R-1) described above wasadded to 100 parts by weight of liquid crystal composition A anddissolution of the compound was attempted by carrying out stirring at25° C. for 3 hours, crystals could be visually confirmed in thecomposition and the mixture was not applicable as a liquid crystalcomposition.

Comparative Example 2

The composition is a liquid crystal composition without containing afirst component of the invention. Components and characteristics of thecomposition were as described below.

3-H2B(2F,3F)-O2 (2-2-1) 20% 5-H2B(2F,3F)-O2 (2-2-1) 15% 3-HBB(2F,3F)-O2(2-5-1) 10% 4-HBB(2F,3F)-O2 (2-5-1) 7% 5-HBB(2F,3F)-O2 (2-5-1) 5%3-HH1OCro(7F,8F)-5 (2-22-1) 7% 2-HH-3 (3-1-1) 24% 3-HH-4 (3-1-1) 3%3-HHB-O1 (3-5-1) 3% 3-HHEBH-3 (3-10-1) 3% 3-HHEBH-4 (3-10-1) 3%

NI=78.3° C.; Tc≦−20° C.; Δn=0.090; Δ∈=−3.8; Vth=1.90 V; τ=6.8 ms;VHR-1=99.2%; VHR-2=98.1%.

Example 1

3-H2B(2F,3F)-O2 (2-2-1) 18% 5-H2B(2F,3F)-O2 (2-2-1) 17%3-HH1OCro(7F,8F)-5 (2-22-1) 6% 3-HBB(2F,3F)-O2 (2-5-1) 10%4-HBB(2F,3F)-O2 (2-5-1) 6% 5-HBB(2F,3F)-O2 (2-5-1) 6% 2-HH-3 (3-1-1) 14%3-HH-4 (3-1-1) 8% 3-HHB-1 (3-5-1) 5% 3-HHB-3 (3-5-1) 6% 3-HHB-O1 (3-5-1)4%

When 0.5 part by weight of compound (1-1) described below was added to100 parts by weight of the liquid crystal composition and dissolution ofthe compound was attempted by carrying out stirring at 25° C. for 3hours, the compound was dissolved. Characteristics of the compositionwere as described below.MAC-B-[HH-5]-B-MAC  (1-1)

NI=78.5° C.; Tc≦−20° C.; Δn=0.092; Δ∈=−3.5; Vth=2.04 V; τ=4.8 ms;VHR-1=99.1%; VHR-2=98.0%.

Moreover, even when 1 part by weight of compound (1-1) described abovewas added to 100 parts by weight of composition A described above anddissolution was attempted by carrying out stirring at 25° C. for 3hours, crystals were completely dissolved. Characteristics of thecomposition were as described below.

NI=78.7° C.; Tc≦−20° C.; Δn=0.092; Δ∈=−3.5; Vth=2.03 V; τ=4.6 ms;VHR-1=99.1%; VHR-2=98.0%.

Example 2

3-H2B(2F,3F)-O2 (2-2-1) 20% 5-H2B(2F,3F)-O2 (2-2-1) 15% 3-HBB(2F,3F)-O2(2-5-1) 10% 4-HBB(2F,3F)-O2 (2-5-1) 7% 5-HBB(2F,3F)-O2 (2-5-1) 5%3-HH1OCro(7F,8F)-5 (2-22-1) 7% 2-HH-3 (3-1-1) 24% 3-HH-4 (3-1-1) 3%3-HHB-O1 (3-5-1) 3% 3-HHEBH-3 (3-10-1) 3% 3-HHEBH-4 (3-10-1) 3%

To 100 parts by weight of the composition, 0.3 part by weight ofcompound (1-1) described below was added.MAC-B-[HH-5]-B-MAC  (1-1)

NI=78.7° C.; Tc≦−20° C.; Δn=0.091; Δ∈=−3.8; Vth=1.91 V; τ=4.9 ms;VHR-1=99.2%; VHR-2=98.1%.

Example 3

3-H2B(2F,3F)-O2 (2-2-1) 20% 5-H2B(2F,3F)-O2 (2-2-1) 15% 3-HBB(2F,3F)-O2(2-5-1) 10% 4-HBB(2F,3F)-O2 (2-5-1) 7% 5-HBB(2F,3F)-O2 (2-5-1) 5%3-HH1OCro(7F,8F)-5 (2-22-1) 7% 2-HH-3 (3-1-1) 24% 3-HH-4 (3-1-1) 3%3-HHB-O1 (3-5-1) 3% 3-HHEBH-3 (3-10-1) 3% 3-HHEBH-4 (3-10-1) 3%

To 100 parts by weight of the composition, 0.3 part by weight ofcompound (1-2) described below was added.MAC-B-[H]-B-MAC  (1-2)

NI=78.6° C.; Tc≦−20° C.; Δn=0.091; Δ∈=−3.8; Vth=1.90 V; τ=4.6 ms;VHR-1=99.2%; VHR-2=98.1%.

Example 4

V-HB(2F,3F)-O2 (2-1-1) 15% V-HB(2F,3F)-O4 (2-1-1) 15% 3-HBB(2F,3F)-O2(2-5-1) 10% 4-HBB(2F,3F)-O2 (2-5-1) 8% 5-HBB(2F,3F)-O2 (2-5-1) 5%3-HHB(2F,3CL)-O2 (2-6-1) 3% 4-HHB(2F,3CL)-O2 (2-6-1) 3% 3-HH-4 (3-1-1)5% V-HH-3 (3-1-1) 20% 3-HHB-1 (3-5-1) 4% 3-B(F)BB-2 (3-8-1) 6% 3-HHEBH-3(3-10-1) 3% 3-HHEBH-4 (3-10-1) 3%

To 100 parts by weight of the composition, 0.2 part by weight ofcompound (1-2) described below was added.MAC-B-[H]-B-MAC  (1-2)

NI=76.8° C.; Tc≦−20° C.; Δn=0.104; Δ∈=−3.1; Vth=2.13 V; τ=5.0 ms;VHR-1=99.1%; VHR-2=97.9%.

Example 5

3-HB(2F,3F)-O2 (2-1-1) 10% 3-H2B(2F,3F)-O2 (2-2-1) 10% 5-H2B(2F,3F)-O2(2-2-1) 10% 3-HHB(2F,3F)-O2 (2-3-1) 10% 5-HHB(2F,3F)-O2 (2-3-1) 8%2-BB(2F,3F)B-3 (2-9-1) 7% 2-BB(2F,3F)B-4 (2-9-1) 6% 2-HH-3 (3-1-1) 13%3-HH-O1 (3-1-1) 5% VFF-HH-3 (3-1) 5% 3-HHB-3 (3-5-1) 3% 3-HBB-2 (3-6-1)6% 5-HBB(F)B-2 (3-13-1) 7%

To 100 parts by weight of the composition, 0.3 part by weight ofcompound (1-1) described below was added.MAC-B-[HH-5]-B-MAC  (1-1)

NI=81.2° C.; Tc≦−20° C.; Δn=0.115; Δ∈=−2.6; Vth=2.34 V; τ=4.4 ms;VHR-1=99.2%; VHR-2=98.3%.

Example 6

3-HB(2F,3F)-O2 (2-1-1) 12% 3-HB(2F,3F)-O4 (2-1-1) 12% 3-HBB(2F,3F)-O2(2-5-1) 8% 2-HDhB(2F,3F)-O2 (2-13-1) 7% 2-HH-3 (3-1-1) 18% 1V-HH-3(3-1-1) 8% 3-HB-O2 (3-2-1) 8% V2-BB-1 (3-3-1) 5% 3-HHEH-3 (3-4-1) 3%3-HHEH-4 (3-4-1) 3% V2-HHB-1 (3-5-1) 6% 5-HBB(F)B-2 (3-13-1) 5%5-HBB(F)B-3 (3-13-1) 5%

To 100 parts by weight of the composition, 0.4 part by weight ofcompound (1-1) described below was added.MAC-B-[HH-5]-B-MAC  (1-1)

NI=77.5° C.; Tc≦−20° C.; Δn=0.101; Δ∈=−2.3; Vth=2.33 V; τ=3.6 ms;VHR-1=99.2%; VHR-2=98.4%.

Example 7

V-HB(2F,3F)-O2 (2-1-1) 10% V-HB(2F,3F)-O4 (2-1-1) 10% 3-HHB(2F,3F)-O2(2-3-1) 10% 3-HBB(2F,3CL)-O2 (2-7-1) 8% 2O-B(2F,3F)B(2F,3F)-O6 (2-8) 3%4O-B(2F,3F)B(2F,3F)-O6 (2-8) 3% 2-HH-3 (3-1-1) 8% V-HH-3 (3-1-1) 30%2-BB(F)B-3 (3-7-1) 5% 3-HB(F)HH-5 (3-9-1) 4% 3-HHEBH-3 (3-10-1) 4%5-HBB(F)B-3 (3-13-1) 5%

To 100 parts by weight of the composition, 0.3 part by weight ofcompound (1-2) described below was added.MAC-B-[H]-B-MAC  (1-2)

NI=75.0° C.; Tc≦−20° C.; Δn=0.097; Δ∈=−2.5; Vth=2.28 V; τ=4.2 ms;VHR-1=99.1%; VHR-2=98.0%.

Example 8

3-HB(2F,3F)-O2 (2-1-1) 8% 3-HB(2F,3F)-O4 (2-1-1) 8% 3-HHB(2F,3F)-O2(2-3-1) 8% 5-HHB(2F,3F)-O2 (2-3-1) 6% 3-HHB(2F,3CL)-O2 (2-6-1) 3%2-BB(2F,3F)B-4 (2-9-1) 6% 3-HEB(2F,3F)B(2F,3F)-O2 (2-16-1) 5%3-HEB(2F,3F)B(2F,3F)-O4 (2-16-1) 5% 3-HH1OB(2F,3F,6Me)-O2 (2-18-1) 5%3-H1O-B(2F,3F,6Me)-O2 (2) 3% 2-HH-3 (3-1-1) 17% 7-HB-1 (3-2-1) 6%1V2-BB-1 (3-3-1) 3% V-HHB-1 (3-5-1) 10% 1-BB(F)B-2V (3-7-1) 4%3-HB(F)BH-3 (3-12-1) 3%

To 100 parts by weight of the composition, 0.4 part by weight ofcompound (1-1) described below was added.MAC-B-[HH-5]-B-MAC  (1-1)

NI=85.3° C.; Tc≦−20° C.; Δn=0.112; Δ∈=−2.9; Vth=2.34 V; τ=5.6 ms;VHR-1=99.1%; VHR-2=98.1%.

Example 9

V-HB(2F,3F)-O2 (2-1-1) 10% V-HB(2F,3F)-O4 (2-1-1) 5% 3-HH2B(2F,3F)-O2(2-4-1) 10% 5-HH2B(2F,3F)-O2 (2-4-1) 6% 2-H1OB(2F,3F)-O2 (2-10-1) 7%3-DhHB(2F,3F)-O2 (2-12-1) 5% 3-HDhB(2F,3F)-O2 (2-13-1) 5%3-dhBB(2F,3F)-O2 (2-15-1) 5% 3-HH-4 (3-1-1) 13% V-HH-4 (3-1-1) 9%5-HB-O2 (3-2-1) 6% 1V-HBB-2 (3-6-1) 5% 2-BB(F)B-5 (3-7-1) 8% 5-HBBH-3(3-11-1) 3% 3-HH1OH-3 (3) 3%

To 100 parts by weight of the composition, 0.8 part by weight ofcompound (1-1) described below was added.MAC-B-[HH-5]-B-MAC  (1-1)

NI=82.2° C.; Tc≦−20° C.; Δn=0.103; Δ∈=−3.2; Vth=2.23 V; τ=5.1 ms;VHR-1=99.3%; VHR-2=98.3%.

Example 10

3-H2B(2F,3F)-O2 (2-2-1) 20% 5-H2B(2F,3F)-O2 (2-2-1) 15% 3-HBB(2F,3F)-O2(2-5-1) 10% 5-HBB(2F,3F)-O2 (2-5-1) 8% 5-HDhB(2F,3F)-O2 (2-13-1) 5%3-HH1OCro(7F,8F)-5 (2-22-1) 7% 2-HH-3 (3-1-1) 20% 3-HH-4 (3-1-1) 6%3-HHB-1 (3-5-1) 3% 3-HHB-3 (3-5-1) 3% 3-HHEBH-3 (3-10-1) 3%

To 100 parts by weight of the composition, 0.5 part by weight ofcompound (1-1) described below was added.MAC-B-[HH-5]-B-MAC  (1-1)

NI=75.6° C.; Tc≦−20° C.; Δn=0.090; Δ∈=−3.9; Vth=1.81 V; τ=4.9 ms;VHR-1=99.1%; VHR-2=98.2%.

Example 11

1V2-HB(2F,3F)-O2 (2-1-1) 6% 3-H2B(2F,3F)-O2 (2-2-1) 12% 5-H2B(2F,3F)-O2(2-2-1) 8% 1V2-H2B(2F,3F)-O2 (2-2-1) 5% 1V2-HH2B(2F,3F)-O2 (2-4-1) 4%V-HBB(2F,3F)-O2 (2-5-1) 4% 3-B(2F,3F)B(2F,3F)-O2 (2-8-1) 3%5-HH1OB(2F,3F)-O2 (2-11-1) 3% 3-DhH1OB(2F,3F)-O2 (2-14-1) 3%V-DhH1OB(2F,3F)-O2 (2-14-1) 3% 3-HH2B(2F,3F,6Me)-O2 (2-17-1) 5%3-H1OCro(7F,8F)-5 (2-20-1) 4% V-HH-5 (3-1-1) 13% 1V-HH-4 (3-1-1) 3%V2-HB-1 (3-2-1) 5% 3-HHB-1 (3-5-1) 4% 3-HHB-O1 (3-5-1) 3% V2-BB(F)B-1(3-7-1) 4% 5-B(F)BB-2 (3-8-1) 5% 1O1-HBBH-4 (—) 3%

Into 100 parts by weight of the composition, 0.3 part by weight ofcompound (1-2) described below was added.MAC-B-[H]-B-MAC  (1-2)

NI=75.0° C.; Tc≦−20° C.; Δn=0.104; Δ∈=−3.8; Vth=1.83 V; τ=5.8 ms;VHR-1=99.2%; VHR-2=98.2%.

Example 12

3-H2B(2F,3F)-O2 (2-2-1) 16% 5-H2B(2F,3F)-O2 (2-2-1) 15% 3-HHB(2F,3F)-O2(2-3-1) 10% 5-HHB(2F,3F)-O2 (2-3-1) 5% 3-HBB(2F,3F)-O2 (2-5-1) 8%4-HBB(2F,3F)-O2 (2-5-1) 5% 5-HBB(2F,3F)-O2 (2-5-1) 5% 3-HDhB(2F,3F)-O2(2-13-1) 6% 2-HH-3 (3-1-1) 15% 3-HH-4 (3-1-1) 12% 3-HHB-1 (3-5-1) 3%

To 100 parts by weight of the composition, 0.4 part by weight ofcompound (1-1) described below was added.MAC-B-[HH-5]-B-MAC  (1-1)

NI=79.6° C.; Tc≦−20° C.; Δn=0.091; Δ∈=−3.9; Vth=1.95 V; τ=4.5 ms;VHR-1=99.3%; VHR-2=98.4%.

Example 13

3-H2B(2F,3F)-O2 (2-2-1) 16% 5-H2B(2F,3F)-O2 (2-2-1) 15% 3-HHB(2F,3F)-O2(2-3-1) 10% 5-HHB(2F,3F)-O2 (2-3-1) 5% 3-HBB(2F,3F)-O2 (2-5-1) 8%4-HBB(2F,3F)-O2 (2-5-1) 5% 5-HBB(2F,3F)-O2 (2-5-1) 5% 3-HDhB(2F,3F)-O2(2-13-1) 6% 2-HH-3 (3-1-1) 15% 3-HH-4 (3-1-1) 12% 3-HHB-1 (3-5-1) 3%

To 100 parts by weight of the composition, 0.4 part by weight ofcompound (1-2) described below was added.MAC-B-[H]-B-MAC  (1-2)NI=79.5° C.; Tc≦−20° C.; Δn=0.090; Δ∈=−3.9; Vth=1.93 V; τ=4.3 ms;VHR-1=99.3%; VHR-2=98.4%.

The compound according to Example 1 has a higher solubility in theliquid crystal composition in comparison with the compound according toComparative Example 1. Moreover, the compositions according to Examples2 to 13 have a shorter response time in comparison with the compositionaccording to Comparative Example 2.

INDUSTRIAL APPLICABILITY

The invention provides a liquid crystal composition satisfying at leastone of characteristics such as a high maximum temperature of a nematicphase, a low minimum temperature of the nematic phase, a smallviscosity, a suitable optical anisotropy, a large negative dielectricanisotropy, a large specific resistance, a high stability to ultravioletlight and a high stability to heat, or a liquid crystal compositionhaving a suitable balance regarding at least two of the characteristics.A liquid crystal display device including such a composition is appliedto constitute an AM device having a short response time, a large voltageholding ratio, a large contrast ratio, a long service life and so forth,and thus can be used in a liquid crystal projector, a liquid crystaltelevision and so forth.

What is claimed is:
 1. A liquid crystal composition containing at leastone compound selected from the group of compounds represented by formula(1) as a first component:

wherein R¹ is hydrogen or alkyl having 1 to 20 carbons, and in thealkyl, arbitrary —CH₂— may be replaced by —O—, —CH═CH— or —C≡C—, R² andR³ are hydrogen or methyl; A¹ is a single bond, 1,4-phenylene or1,4-cyclohexylene; Z¹ is a single bond or alkylene having 1 to 3carbons; Z² is —O— or alkylene having 1 to 6 carbons; Z³ is a singlebond or —O—; Z⁴ is a single bond or alkylene having 2 to 20 carbons, andin the alkylene, arbitrary —CH₂— may be replaced by —O—; X¹ is hydrogen,halogen, alkyl having 1 to 3 carbons or fluoroalkyl having 1 to 3carbons; a is 0 or 1; and in the formula, arbitrary hydrogen on anarbitrary phenylene ring may be replaced by methyl, cyclohexyl orhalogen.
 2. The liquid crystal composition according to claim 1, whereinA¹ is a single bond or 1,4-cyclohexylene, a is 0 and X¹ is hydrogen oralkyl having 1 to 3 carbons.
 3. The liquid crystal composition accordingto claim 1, wherein a ratio of the first component is in the range of0.05 part by weight to 10 parts by weight based on 100 parts by weightof a liquid crystal composition excluding the first component.
 4. Theliquid crystal composition according to claim 1, further containing atleast one compound selected from the group of compounds represented byformula (2) as a second component:

wherein R¹¹ and R¹² are independently alkyl having 1 to 12 carbons,alkoxy having 1 to 12 carbons or alkenyl having 2 to 12 carbons, oralkenyl having 2 to 12 carbons in which arbitrary hydrogen is replacedby fluorine; ring B and ring D are independently 1,4-cyclohexylene,1,4-phenylene, 1,4-phenylene in which arbitrary hydrogen is replaced byfluorine or chlorine, or tetrahydropyran-2,5-diyl; ring C is2,3-difluoro-1,4-phenylene, 2-chloro-3-fluoro-1,4-phenylene,2,3-difluoro-5-methyl-1,4-phenylene, 3,4,5-trifluoronaphthalene-2,6-diylor 7,8-difluorochroman-2,6-diyl; Z¹¹ and Z¹² are independently a singlebond, ethylene, methyleneoxy or carbonyloxy; and m is 1, 2 or 3, n is 0or 1, and a sum of m and n is 3 or less.
 5. The liquid crystalcomposition according to claim 4, wherein the second component is atleast one compound selected from the group of compounds represented byformula (2-1) to formula (2-23):

wherein R¹¹ and R¹² are independently alkyl having 1 to 12 carbons,alkoxy having 1 to 12 carbons or alkenyl having 2 to 12 carbons, oralkenyl having 2 to 12 carbons in which arbitrary hydrogen is replacedby fluorine.
 6. The liquid crystal composition according to claim 4,wherein a ratio of the second component is in the range of 10% by weightto 90% by weight based on the weight of a liquid crystal compositionexcluding the first component.
 7. The liquid crystal compositionaccording to claim 1, further containing at least one compound selectedfrom the group of compounds represented by formula (3) as a thirdcomponent:

wherein R¹³ and R¹⁴ are independently alkyl having 1 to 12 carbons,alkoxy having 1 to 12 carbons or alkenyl having 2 to 12 carbons, oralkenyl having 2 to 12 carbons in which arbitrary hydrogen is replacedby fluorine; ring E and ring F are independently 1,4-cyclohexylene,1,4-phenylene, 2-fluoro-1,4-phenylene or 3-fluoro-1,4-phenylene, Z¹³ isindependently a single bond, ethylene, methyleneoxy or carbonyloxy; andp is 1, 2 or
 3. 8. The liquid crystal composition according to claim 7,wherein the third component is at least one compound selected from thegroup of compounds represented by formula (3-1) to formula (3-13):

wherein R¹³ and R¹⁴ are independently alkyl having 1 to 12 carbons,alkoxy having 1 to 12 carbons or alkenyl having 2 to 12 carbons, oralkenyl having 2 to 12 carbons in which arbitrary hydrogen is replacedby fluorine.
 9. The liquid crystal composition according to claim 7,wherein a ratio of the third component is in the range of 10% by weightto 90% by weight based on the weight of a liquid crystal compositionexcluding the first component.
 10. The liquid crystal compositionaccording to claim 1, further containing a polymerization initiator. 11.The liquid crystal composition according to claim 1, further containinga polymerization inhibitor.
 12. The liquid crystal composition accordingto claim 1, wherein a maximum temperature of a nematic phase is 70° C.or higher, an optical anisotropy (25° C.) at a wavelength of 589nanometers is 0.08 or more, and a dielectric anisotropy (25° C.) at afrequency of 1 kHz is −2 or less.
 13. A liquid crystal display device,comprising two substrates including an electrode layer on at least oneof the substrates, and arranging between the two substrates the liquidcrystal composition according to claim
 1. 14. The liquid crystal displaydevice according to claim 13, wherein an operating mode in the liquidcrystal display device is a TN mode, a VA mode, an IPS mode or a PSAmode, and a driving mode in the liquid crystal display device is anactive matrix mode.
 15. The liquid crystal composition according toclaim 4, further containing at least one compound selected from thegroup of compounds represented by formula (3) as a third component:

wherein R¹³ and R¹⁴ are independently alkyl having 1 to 12 carbons,alkoxy having 1 to 12 carbons or alkenyl having 2 to 12 carbons, oralkenyl having 2 to 12 carbons in which arbitrary hydrogen is replacedby fluorine; ring E and ring F are independently 1,4-cyclohexylene,1,4-phenylene, 2-fluoro-1,4-phenylene or 3-fluoro-1,4-phenylene; Z¹³ isindependently a single bond, ethylene, methyleneoxy or carbonyloxy; andp is 1, 2 or
 3. 16. The liquid crystal composition according to claim15, wherein the third component is at least one compound selected fromthe group of compounds represented by formula (3-1) to formula (3-13):

wherein R¹³ and R¹⁴ are independently alkyl having 1 to 12 carbons,alkoxy having 1 to 12 carbons or alkenyl having 2 to 12 carbons, oralkenyl having 2 to 12 carbons in which arbitrary hydrogen is replacedby fluorine.
 17. The liquid crystal composition according to claim 15,wherein a ratio of the third component is in the range of 10% by weightto 90% by weight based on the weight of a liquid crystal compositionexcluding the first component.